Merfolk of the Depths

Target creature gets +1/+1 and gains flying and first strike until end of turn.

Exile target creature or enchantment.

Flying At the beginning of each combat, choose first strike, vigilance, or lifelink. Creatures you control gain that ability until end of turn.

Flying

Defender Extort (Whenever you cast a spell, you may pay W/B. If you do, each opponent loses 1 life and you gain that much life.)

Extort (Whenever you cast a spell, you may pay W/B. If you do, each opponent loses 1 life and you gain that much life.) Artifacts and creatures your opponents control enter tapped.

Battalion — Whenever this creature and at least two other creatures attack, this creature gets +2/+2 until end of turn.

Whenever another white creature you control enters, tap target creature an opponent controls.